third_party/WebKit: fix typos found in comments

third_party/WebKit/Source/core/paint/PaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2262 matching lines @@
 
     m_compositedLayerMapping = adoptPtr(new CompositedLayerMapping(*this));
     m_compositedLayerMapping->setNeedsGraphicsLayerUpdate(GraphicsLayerUpdateSubtree);
 
     updateOrRemoveFilterEffectBuilder();
 }
 
 void PaintLayer::clearCompositedLayerMapping(bool layerBeingDestroyed)
 {
     if (!layerBeingDestroyed) {
-        // We need to make sure our decendants get a geometry update. In principle,
+        // We need to make sure our descendants get a geometry update. In principle,
         // we could call setNeedsGraphicsLayerUpdate on our children, but that would
         // require walking the z-order lists to find them. Instead, we over-invalidate
         // by marking our parent as needing a geometry update.
         if (PaintLayer* compositingParent = enclosingLayerWithCompositedLayerMapping(ExcludeSelf))
             compositingParent->compositedLayerMapping()->setNeedsGraphicsLayerUpdate(GraphicsLayerUpdateSubtree);
     }
 
     m_compositedLayerMapping.clear();
 
     if (!layerBeingDestroyed)
@@ skipping 444 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif